Crossmember qustions

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smallchevy

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Hi guys I have a 75 k20 just a starting to put powertrain in it have bought it without drive train putting 400/205 in it tring to figure out crossmember right one came off the frame left one i was told was for a 205 but the more i search to makesure i do it once i am findimg a w crossmember witch one should i be trying to get ready to assemble truck thanks
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bucket

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What year is your 400/205 combo? If you have a round pattern case, neither of those will work. If you have a "figure 8" pattern case, both of those crossmembers will work.
 

nvrenuf

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If I’m not mistaken, the crossmember on the left is an 81-84 version (indicated by the bottom lips being irregular shaped vs the straight edges on the right.

I’ve been trying to figure out what dictated the style on the right that wraps up the side of the frame, I’m thinking it’s either exhaust or the skid plate option that used dual crossmembers.

As stated, either will work if you have a tall style adapter. This is just trivia.
 

bucket

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If I’m not mistaken, the crossmember on the left is an 81-84 version (indicated by the bottom lips being irregular shaped vs the straight edges on the right.

I’ve been trying to figure out what dictated the style on the right that wraps up the side of the frame, I’m thinking it’s either exhaust or the skid plate option that used dual crossmembers.

As stated, either will work if you have a tall style adapter. This is just trivia.

I'm not sure about the one on the right either. I've had a couple skid plate trucks with the double crossmember and they didn't have that one. Whatever they were used on, they are seemingly extremely uncommon.
 

Old Guy Bill

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The one on the right looks kinda like mine, a ‘78 with a 400/203 combo
Not sure about that extra bend on the top side though…
 

bucket

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The one on the right with the kickup is the only one I don't have. I think.

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Ricko1966

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The one on the right with the kickup is the only one I don't have. I think.

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I put the laugh emoji,because who would have that many crossmembers at thier disposal.
 

78C10BigTen

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The one on the right with the kickup is the only one I don't have. I think.

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Bottom pic, top x member looks like the one my 78 c10 has. I never put the top brackets back on because after 3 trans i gave up, expecting to do it again.
 

bucket

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Bottom pic, top x member looks like the one my 78 c10 has. I never put the top brackets back on because after 3 trans i gave up, expecting to do it again.

Yours is the 2wd version though, which has a different center area. My C20 Burb has the same one as yours.
 

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